how do ebay sellers make money on prepaid sim cards w/preloaded airtime?

[crypticlogin]

So I've been looking at getting an unlocked GSM phone and a prepaid SIM card from eBay, but it's always struck me as odd: how can these guys who sell the cards, which are sometimes loaded with $20-$60 of airtime credit, make it worthwhile selling them for less than half of face value?

Is there some kind of scam involved?



(and no, every postpaid plan from all the major carriers is way too much for my usage)

 

[AgentJean]

I bought 1 prepaid sim card off Ebay in the passed and it worked out ok.

 

[deadlyapp]

They probably can get it at some sort of wholesale, same as like, 7 11 selling phone cards.